Wear gloves or put something over your hands so that rust bits and fiberglass don't cut your hands up.
Try looking at a diagram of how the bulbs are facing. Unless you have massively huge hands and/or arthiritis, they should be easily accessible. You can even crouch down with a flashlight and look up into the bumper to take a look (wear something to protect your eyes though; there is often a lot of rust crumbs/dust/dirt up there).
If you are still having bad luck, ask someone with smaller hands to do it for you. Reach up and in with your fingers, grasp the bulb at it's base (where the wires meet) and twist and pull down.